Tectonic activity in Mars' past

Here's very interesting stuff... with some nice pics.

The grabens of Claritas Fossae

These images, taken by the High Resolution Stereo Camera (HRSC) on board ESA’s Mars Express spacecraft, show the Claritas Fossae tectonic grabens and part of the Solis Planum plains.

The Claritas Fossae (‘fossa’ is Latin for trough) region is characterised by systems of ‘grabens’ running mainly north-west to south-east. These can be traced several hundred kilometres up to the northern Tharsis shield volcanoes.

A graben forms when a block of the planet’s crust drops down between two faults, due to extension, or pulling, of the crust.

Grabens are often seen together with features called ‘horsts’, which are upthrown blocks lying between two steep-angled fault blocks.
A ‘horst and graben’ system can occur where there are several parallel faults.

Geographically, the grabens separate the eastern volcanic plains of the Solis Planum region from the western Daedalia Planum lava plains.

Deep faults and disrupted crater at Acheron Fossae

These images were taken by the High Resolution Stereo Camera (HRSC) on board ESA’s Mars Express of the Acheron Fossae region, an area of intensive tectonic (continental ‘plate’

activity in the past.

The images in colour, high-resolution and 3D show spectacular curved depressions that have opened the surface, up to 1700 metres deep, through faulting in the Acheron mountain ranges.

Acheron Fossae marks the northern edge of the Tharsis plateau. It is part of a network of extensional fractures that radiates outward from their central focus in the Tharsis ‘bulge’, a huge area of regional uplift where intensive volcanic activity occurred.
These curved ‘faults’ were caused in the process of this uplift: cracks in the crust formed when the hot material rising from deep in the mantle of Mars pushed the overlying ‘elastic’ lithosphere (surface layers of rock) upward. When the distorting tensions became too strong, the brittle crust on top of the lithosphere broke along zones of weakness.

Looks like nice terrain, doesn't it?
They won't be sending rovers to there definitely.


www.marstoday.com...

Now, if you thought that Mars was almost perfectly round, think again! The red planet has a large bulge sticking out from it called Tharsis. Almost 3,000 miles across, this enormous region rises almost four miles above the average radius of the planet. That’s quite a bulge!

Since Tharsis is the land of the largest volcanoes in the solar system, it may have been formed by both the uplift of land from tectonic action and the build-up of lava flows. Tharsis can cause some pretty major tectonic disruptions across the planet when it tries to settle down from its height and reach a better equilibrium with the rest of the planet.

On Earth, a similar series of rift valleys (grabens) formed by crustal extension too. The East African Rift System began forming almost 30 million years ago due to volcanic activity that also created most of the high peaks in East Africa, including the famous Kilimanjaro. This African peak is so high it always has snow on top of it, even though it’s located right near the equator. That height might remind you of the towering Martian volcanoes in Tharsis. The East African Rift Valley System also formed over large domes that were created as hot molten material beneath the Earth’s surface welled up, pushing up the crust and causing it to expand and stretch. This stretching caused the rift valleys (grabens) to appear here on our own planet.

Claritas Fossae tectonic region on Mars
Geography on Mars

Other pages about volcanism in Mars.
www.solarviews.com...
volcano.und.edu...